General-purpose wheatstone bridge

Definition

A general-purpose Wheatstone bridge is a circuit used for measuring electrical resistance by balancing two legs of a bridge circuit. This device allows for precise measurement of unknown resistances by comparing them with known resistances, enabling accurate readings in various applications like strain gauges, temperature sensors, and more.

5 Must Know Facts For Your Next Test

1. The Wheatstone bridge operates on the principle of null measurement, where no current flows through the galvanometer when the bridge is balanced.
2. It consists of four resistors arranged in a diamond shape, with a galvanometer and a power source connected across two opposite junctions.
3. To find an unknown resistance, you adjust the known resistors until the galvanometer shows zero current, indicating a balanced condition.
4. The accuracy of measurements using a Wheatstone bridge depends on the precision of the known resistors used in the circuit.
5. General-purpose Wheatstone bridges can be adapted for different measurement applications, such as temperature changes using thermistors or strain measurements using strain gauges.

Review Questions

• How does a general-purpose Wheatstone bridge enable the measurement of unknown resistances?
  • A general-purpose Wheatstone bridge measures unknown resistances by balancing two legs of a circuit. By adjusting known resistances until there is no current detected in the galvanometer, you achieve a balanced state. This balance occurs when the ratios of the known resistances match those of the unknown resistance, allowing for precise calculations of its value using Ohm's Law.
• Discuss how changes in temperature can affect measurements made with a Wheatstone bridge and what adjustments might be necessary.
  • Temperature variations can influence both the unknown resistance and the known resistors within a Wheatstone bridge due to resistance changes associated with temperature effects. To maintain accuracy, it may be necessary to recalibrate the known resistors or compensate for temperature effects using materials with predictable resistance-temperature characteristics. Understanding these factors helps ensure reliable measurements across varying environmental conditions.
• Evaluate how a general-purpose Wheatstone bridge can be utilized in different fields, including engineering and medical applications, and what advantages it offers.
  • A general-purpose Wheatstone bridge is valuable in various fields such as engineering for material stress analysis and in medical devices for precise measurements of bodily parameters like pressure or temperature. Its main advantage lies in its ability to provide highly accurate resistance measurements while being adaptable to different sensor technologies. This versatility allows engineers and medical professionals to ensure optimal performance and reliability of their instruments, making it an essential tool across multiple disciplines.

Related terms

Ohm's Law:

A fundamental principle stating that the current through a conductor between two points is directly proportional to the voltage across the two points.

Resistance:

The opposition that a substance offers to the flow of electric current, measured in ohms.

Balanced Bridge: A condition in which the ratio of resistances in one leg of the bridge is equal to the ratio in the other leg, resulting in zero voltage difference across the bridge.